Mutual capacitive touch panel

ABSTRACT

The present invention provides a mutual capacitive touch panel, including: a plurality of driving lines; a plurality of sensing lines intersecting with the plurality of driving lines; a signal output unit disposed at input ends of the driving lines is configured to simultaneously output driving signals with different frequencies to all the driving lines; a preamplifier disposed at output ends of the sensing lines is configured to capture sensing signals from the sensing lines, and amplify the sensing signals and then output the amplified sensing signals to a signal separation unit; the signal separation unit connected to the preamplifier is configured to separate the sensing signals with different frequencies and obtain addresses of the driving lines corresponding to the sensing signals. The signal output unit determines the frequency sequence of the driving signals every the first predetermined time interval based on the hopping rule, and changes the frequency of the driving signal of each of the columns of the driving lines based on the determined frequency sequence.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 14/347,232, filed Mar. 25, 2014, which is a U.S.National Stage Application filed under § 371 of PCT/CN2012/084199, filedNov. 7, 2012, and entitled “MUTUAL CAPACITIVE TOUCH SCREEN”, whichclaims the benefit of Chinese Patent Application No. 201210303977.1,filed Aug. 23, 2012 and entitled “MUTUAL CAPACITIVE TOUCH SCREEN”, thecontents of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to the field of touch screen technologies,in particular to a mutual capacitive touch panel.

BACKGROUND OF THE INVENTION

Depending on sensing signal detecting modes of capacitive touch panels,the capacitive touch panels include self capacitive touch panels andmutual capacitive touch panels.

As shown in FIG. 1, a mutual capacitive touch panel contains a pluralityof driving lines (for example Y1 to Y4) and a plurality of sensing lines(for example X1 to X4) intersecting with the driving lines. A sub-pixelof the touch panel is surrounded by a dashed box. A capacitance causedby the overlapping portions of the driving line and the sensing linewill not be influenced by an external touching object, but will cause asteady background noise or a Direct Current (DC) component inputted to apreamplifier A. However, a mutual capacitance Cm that is formed by aspatial fringe electric field generated between the non-overlappedportions of electrodes of the driving lines and the sensing lines willbe influenced directly by the external touching objects.

An equivalent circuit of a typical mutual capacitive touch panel asshown in FIG. 1 works in principle as described simply as follows:driving signals with a specific frequency are inputted one by onethrough ends of the driving lines, and signals with the same frequencyinduced by the mutual capacitance Cm between the driving lines and thesensing lines are received and amplified by the preamplifier A connectedto ends of the sensing lines. When the surface of the touch panel istouched by a finger of a user, parasitic capacitances are formed betweenthe finger and the driving lines and between the finger and the sensinglines. A portion of the signals will be directly leaked to the groundthrough the user's body or the grounded object via the parasiticcapacitance, thus the signals received by the preamplifier A arepreviously attenuated. Depending on the design for the electrode of thetouch panel, the driving frequency and the distance between the user'sfinger and the electrode of the touch panel, the driving signals mightbe coupled from the driving lines to the sensing lines through a mediumsuch as the user's finger, thereby the signals received by thepreamplifiers A are increased. In both signal induction modes, aspecific position touched by the finger T can be easily found out bydetecting the signal changes in the sensing lines one by one.

In the prior art, driving signals with a specific frequency are inputtedone by one to the input ends of the driving lines. When a finger touchesthe touch panel, the mutual capacitance between the driving line and thesensing line is changed so that the amplitude of the signal of thespecific frequency received from the sensing line by a detection deviceis varied accordingly. Each of such driving signals of a specificfrequency is necessarily inputted to each of the driving lines, that is,the driving lines are scanned by specific pulse signals. According tothis method in the prior art, the circuitry becomes very complicated andcostly in the case of a large number of the driving lines or thehigh-speed detection.

BRIEF SUMMARY OF THE INVENTION

The embodiments of the present invention provide a mutual capacitivetouch panel, in which all the driving lines are synchronously driven forhigh-speed driving, and the circuitry is simple, to reduce the cost ofthe entire touch panel and improve the response uniformity of the outputsignals of the mutual capacitive touch panel when being touched.

Embodiments of the present invention provide a mutual capacitive touchpanel, including: a plurality of driving lines; a plurality of sensinglines intersecting with the plurality of driving lines; at least onepreamplifier; a signal output unit; and a signal separation unit.

In the touch panel, the signal output unit is disposed at input ends ofthe driving lines and is configured to simultaneously output drivingsignals with different frequencies to all the driving lines.

In the touch panel, the preamplifier is disposed at output ends of thesensing lines and is configured to capture sensing signals from thesensing lines, and amplify the sensing signals and output the amplifiedsensing signals to the signal separation unit.

In the touch panel, the signal separation unit is connected to thepreamplifier and is configured to separate the sensing signals withdifferent frequencies and obtain addresses of the driving linescorresponding to the sensing signals.

In the touch panel, the signal output unit determines the frequencysequence of the driving signals every the first predetermined timeinterval based on the hopping rule, and changes (i.e., hops) thefrequency of the driving signal of each of the columns of the drivinglines based on the frequency sequence.

The present invention has the following advantages as compared with theprior art.

In the mutual capacitive touch panel provided in the present invention,driving signals with different frequencies are outputted by the signaloutput unit to each of the driving lines respectively, instead ofdriving signals with a specific frequency are outputted to the inputends of the driving lines one by one in the prior art. In the case of alarge number of driving lines, the driving signals with differentfrequencies are sent to different driving lines simultaneously by thesignal output unit in the present invention. However, the drivingsignals are sent one by one in the prior art, which causes not only timedelays but also complicated control, because the driving lines arerequired to be connected and conducted one by one to send the drivingsignals. The touch panel provided in the present invention has simplecircuitry and is convenient to control. Furthermore, the frequencysequence of the driving signals is determined every the firstpredetermined time interval based on the hopping rule, and the frequencyof the driving signal of each of the columns of the driving lines ischanged based on the frequency sequence, so that the frequencydifference of the driving signal on driving lines is averaged, in orderto improve the response uniformity of the output signals of the mutualcapacitive touch panel when being touched.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing the typical mutual capacitive touchpanel in the prior art;

FIG. 2 is a schematic view of a mutual capacitive touch panel accordingto an embodiment of the present invention;

FIG. 3 is a circuit diagram of the mutual capacitive touch panelaccording to another embodiment of the present invention;

FIG. 4 is a circuit diagram of the mutual capacitive touch panelaccording to another embodiment of the present invention;

FIG. 5 is a circuit diagram of the mutual capacitive touch panelaccording to another embodiment of the present invention.

FIG. 6 is a schematic view showing hopping of the frequencies of thedriving signals according to an embodiment of the present invention;

FIG. 7 is a schematic view showing hopping of the frequencies of thedriving signals according to another embodiment of the presentinvention; and

FIG. 8 is a schematic view showing hopping of the frequencies of thedriving signals according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention are further described inconjunction with the accompanying drawings so as to make the objects,characteristics and advantages of the present invention more apparent.

In order to reduce the complexity of the circuitry and the cost, drivingsignals with different frequencies may be inputted to different drivinglines simultaneously. After performing a primary amplification on allthe output signals with frequencies, the detection device separates theamplified output signals with different frequencies using the narrowbanddivider, and the address of the driving line corresponding to the eachof the driving signals is determined automatically based on thefrequency of the driving signal, and then the touch position is analyzedbased on the amplitude of the attenuated signal or enhanced signal. Whenthe touch panel is relatively large, the number of driving lines andsensing lines would increases accordingly, and therefore it is necessaryto synchronously input driving signals with different frequencies to thelarge number of driving lines, leading to widen the frequency domain.However, due to a big difference between the frequencies of the drivingsignals on the driving lines, a big difference between the outputsignals occurs, so that responses of the signal of the touch panel arenot uniform.

Referring to FIG. 2, which shows a schematic view of a mutual capacitivetouch panel according to an embodiment of the present invention.

The mutual capacitive touch panel provided in the present embodimentincludes: a plurality of driving lines Y, a plurality of sensing lines Xintersecting with the driving lines, a preamplifier A, a signal outputunit 100 and a signal separation unit 200.

The signal output unit 100, which is disposed at an input end of thedriving lines Y, is configured to simultaneously output driving signalswith different frequencies to all the driving lines Y.

The preamplifier A, which is disposed at an output end of the sensinglines X, is configured to capture sensing signals in the sensing linesX, and amplify and then output the sensing signals to the signalseparation unit 200.

The signal separation unit 200, which is connected to the preamplifierA, is configured to separate the sensing signals with differentfrequencies and obtain addresses of the driving lines Y corresponding tothe sensing signals, respectively.

In the mutual capacitive touch panel provided in the present embodiment,the driving signals with different frequencies are outputted by thesignal output unit 100 to each of the driving lines Y, respectively,instead of outputting driving signals with a specific frequency to theinput ends of the driving lines one by one in the prior art. In the caseof a large number of the driving lines Y, the driving signals withdifferent frequencies can be simultaneously sent by the signal outputunit 100 to the different driving lines Y, respectively, and the sensingsignals are eventually separated by the signal separation unit 200 tofurther identify the specific positions of the sensing signals, so thatthe driving line that sends the driving signal inducing the sensingsignals can be determined However, the driving signals are required tobe sent one by one in the prior art, which causes not only time delaysbut also the complicated control, because the driving lines Y arerequired to be connected and conducted one by one to send the drivingsignals. The touch panel provided in the present embodiment has simplecircuitry and is convenient to control. Since the frequency of thedriving signal outputted to each of the driving lines is different fromthe frequencies of the driving signals outputted to the other of thedriving lines, the driving signals in the driving lines are notinterfered by each other.

It is noted that only one signal output unit 100 is provided in theembodiment of the present invention to output the driving signals withdifferent frequencies for all the driving lines Y.

Alternatively, a plurality of the signal output units 100 may beprovided in the embodiment of the present invention to output thedriving signals with different frequencies to the corresponding drivinglines Y. For example, a first signal output unit is configured to outputdriving signals to the first to the Mth driving lines, and a secondsignal output unit is configured to output driving signals to the(M+1)th to the Nth driving lines, wherein M and N are integers and M<N.Of course, it is also possible that each of the signal output unitscorresponds to each of the driving lines.

It is noted that the signal output unit 100 may be a signal generator.The driving signals with different frequencies can be generated by thesignal generator with configured parameters.

Reference is now made to FIG. 3, which shows a circuit diagram of themutual capacitive touch panel according to a second embodiment of thepresent invention.

In the mutual capacitive touch panel provided in this embodiment, theoutput end of each of the sensing lines X is connected to a preamplifierA.

As shown in FIG. 3, the present embodiment is described by an examplewith three driving lines Y1, Y2 and Y3 and two sensing lines X1 and X2.

As can be seen from FIG. 3, the output end of each of the sensing linesis connected to a preamplifier. For example, the output end of a sensingline X1 is connected to a first preamplifier A1 and the output end of asensing line X2 is connected to a second preamplifier A2.

It is noted that, in the present embodiment, the preamplifier furtherincludes a feedback network, and the feedback network includes at leasttwo feedback branches connected in parallel, where one of the feedbackbranches includes a resistor and the other of the feedback branchesincludes a resistor and a switch connected in series, and the resistanceof the feedback network may be changed by controlling the on and off ofthe switch.

The first preamplifier A1 is taken as an example for describing below.Referring to FIG. 3, the feedback network in the first preamplifier A1includes two feedback branches, a first feedback branch of whichincludes a first resistor Rf1, while a second feedback branch of whichincludes a second resistor Rf2 and a first switch Sf2 connected inseries. When the first switch Sf2 is closed, the feedback networkincludes two resistors connected in parallel (i.e. the first resistorRf1 and the second resistor Rf2); and when the first switch Sf2 is off,the feedback network includes the first resistor Rf1. That is, theresistance of the feedback network is changed by controlling the on andoff of the first switch Sf2.

The preamplifier further includes a compensation network containing acompensation resistor Rref, and an inverting input terminal of thepreamplifier is connected to a compensation signal source via thecompensation resistor Rref.

The function of the compensation network is to compensate the outputsignal of the preamplifier when no signal is outputted by the sensinglines of the touch panel, so as to prevent the output terminal of thepreamplifier from outputting a signal which leads to incorrectidentification of the existence of a sensing signal in the touch panel.

The feedback network of the second preamplifier A2 is as same as that ofthe first preamplifier A1, and thus will not be described in detailherein.

In this embodiment, a positive phase input terminal of the preamplifieris connected to a bias voltage Vref and the inverting input terminal ofthe preamplifier is connected to the output end of the correspondingsensing line.

It is noted that the signal separation unit 200 may be a band-passfilter, through which the signals of frequencies corresponding to thedriving signals are allowed to pass through, but signals of otherfrequencies are filtered out by the band-pass filter.

The number of the band-pass filters connected to the output end of eachof the preamplifiers is equal to that of the driving lines. As shown inFIG. 3, the band-pass filters connected to the output end of the firstpreamplifier A1 include a first band-pass filter F1, a second band-passfilter F2 and a third band-pass filter F3. The band-pass filtersconnected to the output end of the second preamplifier A2 include afourth band-pass filter F4, a fifth band-pass filter F5 and a sixthband-pass filter F6.

As can be seen from FIG. 3, the output end of each of the sensing linesis connected to one preamplifier, and the circuitry structure willbecome very complicated in the case of a large number of sensing lines.An embodiment is further provided to decrease the complexity of thecircuitry structure. Reference is made below to FIG. 4, which is acircuit diagram of the mutual capacitive touch panel according to athird embodiment of the present invention.

As compared with the second embodiment, all the output terminals ofpreamplifiers connected to the sensing lines are connected to a shiftregister through selection switches in the present embodiment, therebyreducing the number of the band-pass filters, where the number of theselection switches is equal to that of the sensing lines.

As shown in FIG. 4, in the present embodiment, there are three drivinglines Y1, Y2 and Y3, two sensing lines X1 and X2, a first preamplifierA1 and a second preamplifier A2 that are connected to the output ends ofthe sensing lines, a first selection switch S1 and a second selectionswitch S2 respectively connected in series with output terminals of thepreamplifiers, and a shift register SR.

An output signal of the shift register SR is provided to a control gateof each of the selection switches, e.g., to the control gates of both ofthe first selection switch S1 and the second selection switch S2 asshown in FIG. 4; and, the sensing signals from the sensing lines X1 andX2 are amplified by the corresponding preamplifier, and then theamplified sensing signals are selected by the shift register SR bycontrolling the turning on or off of the first selection switch S1 andthe second selection switch S2. The phases of the pulse signalsoutputted by the shift register SR are delayed sequentially by apredetermined cycle, the selection switches are selectively turned onsequentially, thus the sensing signals from the sensing lines passthrough only one set of band-pass filters F1, F2 and F3, that is,signals with different frequencies from the driving lines Y1, Y2 and Y3are separated by the single set of band-pass filters F1, F2 and F3.Therefore, those three band-pass filters F4, F5 and F6 corresponding tothe preamplifier A2 in FIG. 3 are omitted. In other words, only one setof band-pass filters are required for detecting the touch position,thereby reducing the complexity of the circuit, decreasing the controldifficulty and saving the cost.

An embodiment of the present invention is further provided to furtherdecrease the complexity of the circuitry structure. Reference is nowmade to FIG. 5, which is a circuit diagram of the mutual capacitivetouch panel according to a fourth embodiment of the present invention.

A shift register SR is added to the output ends of the sensing lines inthis embodiment such that the output ends of all the sensing lines areconnected to the same preamplifier, and the number of band-pass filtersis reduced as well.

As shown in FIG. 5, the touch panel provided in this embodiment furtherincludes a shift register SR and selection switches, where the number ofthe selection switches is equal to that of the sensing lines. Twosensing lines X1 and X2 are present in the present embodiment, thusthere are two selection switches corresponding to the sensing lines X1and X2, i.e. a first selection switch S1 and a second selection switchS2, but there is only one preamplifier, i.e. the preamplifier A as shownin FIG. 5.

An output end of each of the sensing lines is connected to one selectionswitch in series. As shown in FIG. 5, the output end of the sensing lineX1 is connected to the first selection switch S1 in series, and theoutput end of the sensing line X2 is connected to the second selectionswitch S2 in series.

An output signal of the shift register SR is provided to a control gateof each of the selection switches, e.g., to control gates of both of thefirst selection switch S1 and the second selection switch S2 as shown inFIG. 5. Sensing signals outputted by the sensing line X1 or X2 isselected by the shift register SR through controlling the turning on andoff of the first selection switch S1 and the second selection switch S2.The sensing signals outputted by the sensing lines X1 and X2 areinputted to the inverting input terminal of the preamplifier A, whilethe positive phase input terminal of the preamplifier A is connected toa bias voltage Vref.

The phases of the pulse signals outputted by the shift register SR aredelayed sequentially by a predetermined cycle, so that the selectionswitches are sequentially turned on selectively, to output the signalsfrom the sensing lines to the inverting input terminal of thepreamplifier. Therefore, the number of the preamplifier can bedecreased, that is, only one preamplifier is provided for the outputends of all the sensing lines, thereby greatly reducing the complexityof the circuit as well as the control difficulty, and saving the cost.

Similarly, since the number of the preamplifiers is decreased, thenumber of band-pass filters connected to the output terminal of thepreamplifier is decreased accordingly.

It is noted that, in the mutual capacitive touch panel provided in thisembodiment, the end of each sensing line, from which the sensing signalis outputted, is connected to a first end of the selection switch by avia hole disposed on the thin film transistor substrate or a conductivegold spacer, and the second ends of all the selection switches areconnected to the input terminal of the preamplifier.

The principle of the present embodiment will be described as follows inconjunction with FIG. 5.

For example, a frequency f1 of the driving signal in a first column ofdriving line is 50 kHz;

a frequency f2 of the driving signal in a second column of driving lineis 60 kHz; and

a frequency f3 of the driving signal in a third column of driving lineis 70 kHz.

After the signals are separated by the band-pass filter, it can beconcluded that a specific position on the second column of the drivingline Y2 is touched if the amplitude of a signal with a frequency of 60kHz is changed.

If the signal of the sensing line is from the second selection switchS2, it can be concluded that the second row of the sensing line X2 istouched. Therefore, it is determined that coordinates of the specificposition touched by the user's finger is (2, 2).

In the technical scheme above, the signal output unit 100 simultaneouslyoutputs driving signals with different frequencies to all the drivinglines Y, with each of the driving lines Y receiving a driving signalwith a fixed frequency, so that the signal separation unit 200 canacquire the addresses of the sensing lines X and the driving lines Ycorresponding to the touch position, when a sensing signal with acertain frequency from the sensing lines obtained by the signalseparation unit 200 is changed.

To ensure that the signal separation unit 200 can distinguish thesensing signals with different frequencies, and to reduce the mutualinterference of the driving signals with different frequencies, thefrequencies difference between the input frequency of each driving lineand the input frequency of other driving lines must be greater or equalto the minimum frequency difference Δf (e.g. 1 KHz to 100 KHz). In thecase that the area of the mutual capacitive touch panel is changedlarger, or the mutual capacitive touch panel with a fixed area hashigher resolution, the increased number of the driving lines Y and theincreased number of the sensing lines X would occur, for example, from40 (the number of the driving lines Y)*40 (the number of the sensinglines X) to 400 (the number of the driving lines Y)*400 (the number ofthe sensing lines X). The increased number of the driving lines andsensing lines need the driving signals with wider frequency domain foroutputting. For example, the frequency of the driving signal of thefirst column of diving lines Y1 is 5 MHz, the frequency of the drivingsignal of the second of column diving lines Y2 is 5.01 MHz, thefrequency of the driving signal of the 100th column of diving lines Y100is 6 MHz, the frequency of the driving signal of the 400th column ofdiving lines Y400 is 9 MHz. Consequently, the width of the frequencydomain of the driving signals outputted by the signal output unit 100 is5 MHz-9 MHz. The circuitry within the mutual capacitive touch panel issubstantially a resistor-capacitance (RC) network, and therefore thedelay and the twist effect of the driving signals with differentfrequencies caused by the time constant inherent in the circuit aredifferent, so that the outputted sensing signals generated by thecoupling of the first column of driving lines Y1 and each of the sensinglines X are much different from the outputted sensing signals generatedby the coupling of the 400th column of driving lines Y400 and each ofthe sensing lines X, thereby affecting the response uniformity of thesignals of the mutual capacitive touch panel when being touched.

In order to solve above problem and obtain a wider frequency responseproperty, the signal output unit may change the frequency of the drivingsignal to each of the columns of the driving lines every predeterminedtime interval in the above embodiments of the present invention.However, it is required that the frequency of the driving signal addedto each of the columns of the driving lines is sufficiently differentfrom the frequency of the driving signal added to any other column ofthe driving line, thus the signals with different frequencies can beseparated subsequently by the band-pass filter without interference andcrosstalk caused by signals of other columns.

Specifically, in the embodiment of the present invention, the signaloutput unit determines the sequence of the frequencies of the drivingsignals every the first predetermined time interval based on the hoppingrule, and changes the frequency of the driving signal of each of thecolumns of the driving lines according the frequency sequence result.

In the embodiment of the present invention, many specific methods areprovided to achieve the changing of the frequency of the driving signalof each of the columns of the driving lines, as long as it is ensuredthat for the driving signal of each column of the driving lines, thefrequency of the driving signal before hopping is different from thatafter hopping. The alternative frequency hopping driving schemes will bedescribed in detail hereinafter.

FIG. 6 is a schematic view showing hopping of the frequencies of thedriving signals according to an anther embodiment of the presentinvention. Three driving lines Y1, Y2 and Y3 and two sensing lines X1and X2 are illustratively shown in the present embodiment. As shown inFIG. 6, at the time T1, the driving signal with the frequency f1 isoutputted to the first column driving line Y1 from the signal outputunit 100, the driving signal with the frequency f2 is outputted to thesecond column driving line Y2 from the signal output unit 100, and thedriving signal with the frequency f3 is outputted to the third columndriving line Y3 from the signal output unit 100. After the firstpredetermined time interval Δt1 (that is, at the time T1+Δt1), thedriving signal with the frequency f2 is outputted to the first columndriving line Y1 from the signal output unit 100, the driving signal withthe frequency f3 is outputted to the second column driving line Y2 fromthe signal output unit 100, and the driving signal with the frequency f1is outputted to the third column driving line Y3 from the signal outputunit 100. Then, after the first predetermined time interval Δt1 (thatis, at the time T1+2Δt1), the driving signal with the frequency f3 isoutputted to the first column driving line Y1 from the signal outputunit 100, the driving signal with the frequency f1 is outputted to thesecond column driving line Y2 from the signal output unit 100, and thedriving signal with the frequency f2 is outputted to the third columndriving line Y3 from the signal output unit 100. Namely, the signaloutput unit 100 successively exchanges the current frequencies of thedriving signals on two adjacent driving lines every the firstpredetermined time interval Δt1, and determines the sequence of thefrequencies of the driving signals, and changes (i.e., hops) thefrequency of the driving signal on each column driving line based on thesequence result (that is, the determined sequence) of the frequency. Theabove-mentioned sequence result of the frequencies is: f1, f2, f3; f2,f3, f1; and f3, f1, f2, where the f1, f2, f3 may be in an increasingsequence, a decreasing sequence or a random sequence.

Although in the above embodiment, the frequency of the driving signalfor a single driving line is single, the frequency difference of thedriving signal on the driving line is averaged after multiplesuccessively hopping driving, so that the non-uniformity on the spatialbetween the first column of driving lines and the last column of drivinglines is eliminated, thus solving the problem of the non-uniformresponse of the signals of the mutual capacitive touch panel when beingtouched.

FIG. 7 is a schematic view showing hopping of the frequencies of thedriving signals according to anther embodiment of the present invention.As shown in FIG. 7, the signal output unit randomly changes thefrequency sequence of the driving signals every the first predeterminedtime interval Δt1, and changes the frequency of the signal for eachdriving line based on the randomly-changed frequency sequence of thedriving signals. The sequence result of the frequencies in FIG. 7 is:f1, f3, f2; f1, f3, f3; f1, f2, f3. Specifically, at the time T1, thedriving signal with the frequency f1 is outputted to the first columndriving line Y1 from the signal output unit 100, the driving signal withthe frequency f3 is outputted to the second column driving line Y2 fromthe signal output unit 100, the driving signal with the frequency f2 isoutputted to the third column driving line Y3 from the signal outputunit 100. After one first predetermined time interval Δt1 (that is, atthe time T1+Δt1), the driving signal with the frequency f2 is outputtedto the first column driving line Y1 from the signal output unit 100, thedriving signal with the frequency f1 is outputted to the second columndriving line Y2 from the signal output unit 100, and the driving signalwith the frequency f3 is outputted to the third column driving line Y3from the signal output unit 100; Then, after another first predeterminedtime interval Δt1 (that is, at the time T1+2Δt1), the driving signalwith the frequency f1 is outputted to the first column driving line Y1by the signal output unit 100, the driving signal with the frequency f2is outputted to the second column driving line Y2 from the signal outputunit 100, and the driving signal with the frequency f3 is outputted tothe third column driving line Y3 from the signal output unit 100.

Another method for hopping the frequency of the driving signal is alsoprovided in an embodiment of the present invention. Specifically, thesignal output unit queries a predetermined address code every the firstpredetermined time interval, and determines the sequence of thefrequencies of the outputted driving signals according to thecorresponding hopping rule based in the predetermined address code; andchanges the frequency of the driving signal on each of the columns ofthe driving lines according to the sequence result of the frequencies.

Optionally, the predetermined address code may be defined in advance, ormay be generated in a random and real-time update, as long as the signaloutput unit re-assigns the frequency hopping of the driving signals oneach column of driving lines according to the predetermined address codeso as to ensure that the frequency of driving signal on each column ofdriving lines after the hopping is different from that before thehopping.

The hopping rule, which defines the correspondence relationship betweenthe frequencies of the driving signals and the addresses of the drivinglines in each hopping, is stored in the predetermined address code. Thesignal output unit queries the predetermined address code every thefirst predetermined time interval, and determines the sequence of thefrequencies of the driving signals according to the current hopping rulein the predetermined address code.

FIG. 8 is a schematic view showing hopping of the frequencies of thedriving signals hopping according to an anther embodiment of the presentinvention. As shown in FIG. 8, at the time T1, the frequencies of thedriving signals corresponding to the first column driving line Y1, thesecond column driving line Y2 and the third column driving line Y3 aref2, f1 and f3, respectively. After one first predetermined time intervalΔt1 (that is, at the time T1+Δt1), the signal output unit queries thepredetermined address code and determines the current frequencies of thedriving signals corresponding to the first column driving line Y1, thesecond column driving line Y2 and the third column driving line Y3 asf3, f2 and f1, respectively. Accordingly, the frequencies of the drivingsignals corresponding to the first column driving line Y1, the secondcolumn driving line Y2 and the third column driving line Y3 are changedfrom f2, f1 and f3 to f3, f2 and f1, respectively. After another firstpredetermined time interval Δt1 (that is, at the time T1+2Δt1), thesignal output unit queries the predetermined address code and determinesthe current frequencies of the driving signals corresponding to thefirst column driving line Y1, the second column driving line Y2 and thethird column driving line Y3 as f1, f3 and f2, respectively.Accordingly, the frequencies of the driving signals corresponding to thefirst column driving line Y1, the second column driving line Y2 and thethird column driving line Y3 are changed from f3, f2 and f1 to f1, f3and f2, respectively.

Optionally, the signal output unit may update the hopping rule stored inthe predetermined address code every the second predetermined timeinterval Δt2.

As can be seen, the embodiments described above are preferable but notintended to limit the present invention in any way. Although the presentinvention has been described as above in combination with the preferableembodiments, the invention is not limited to these embodiments. Variousmodifications and variations may be made on the technical solutions ofthe present invention by those skilled in the art in light of themethods and other technical contents described above without departingfrom the scope of the invention, or equivalent embodiments withequivalent modifications may be obtained. Thus, any simplemodifications, equivalent variations and modifications made to theembodiments based on the essence of the technical solution withoutdeparting the scope of the technical solutions of the present inventionare intended to fall within the scope of this invention.

What is claimed is:
 1. A mutual capacitive touch panel, comprising: aplurality of driving lines; a plurality of sensing lines intersectingwith the plurality of driving lines; a preamplifier; a signal outputunit; and a signal separation unit; wherein the signal output unit isdisposed at input ends of the driving lines and is configured tosimultaneously output driving signals to all the driving lines, whereineach of driving signals has a different frequency and is output to adifferent one of the driving lines respectively; wherein thepreamplifier is disposed at output ends of the plurality of sensinglines and is configured to capture sensing signals from the plurality ofsensing lines, amplify the sensing signals and output the amplifiedsensing signals to the signal separation unit; wherein the signalseparation unit is connected to the preamplifier and is configured toseparate the sensing signals with different frequencies and obtainaddresses of the plurality of driving lines associated with each of thesensing signals; wherein the signal output unit determines a frequencysequence every a first predetermined time interval based on a hoppingrule, and changes a frequency of a driving signal of each of the drivinglines based on the determined frequency sequence, wherein the frequencysequence comprises frequencies of the driving signals; wherein themutual capacitive touch panel further comprises a shift register andselection switches, wherein a number of the selection switches is equalto a number of the plurality of sensing lines; wherein an output end ofeach of the plurality of sensing lines is connected with one of theselection switches in series, an output signal of the shift register isprovided to a control gate of each of the selection switches so that asensing signal outputted by one sensing line of the plurality of sensinglines is selected by the shift register through controlling turning onand off of the selection switches, the sensing signal outputted from theplurality of sensing lines is inputted to an inverting input terminal ofthe preamplifier, and wherein a positive phase input terminal of thepreamplifier is connected to a bias voltage.
 2. The mutual capacitivetouch panel of claim 1, wherein the signal output unit randomly changesthe frequency sequence of the driving signals every the firstpredetermined time interval, and changes the frequency of the drivingsignal of each of the columns of the driving lines according to therandomly-changed frequency sequence of the driving signals.
 3. Themutual capacitive touch panel of claim 1, wherein the signal output unitchanges the frequency sequence by successively exchanging the currentfrequencies of the driving signals associated with two adjacent drivinglines every the first predetermined time interval, and changes thefrequency of the driving signal of each of the columns of the drivinglines according to the changed frequency sequence of the drivingsignals.
 4. The mutual capacitive touch panel of claim 1, wherein thesignal output unit queries a predetermined address code every the firstpredetermined time interval, determines the frequency sequence accordingto the hopping rule in the predetermined address code; and changes thefrequency of the driving signal of each of the columns of the drivinglines according to the determined frequencies sequence.
 5. The mutualcapacitive touch panel of claim 4, wherein the predetermined addresscode is updatable.
 6. The mutual capacitive touch panel of claim 1,wherein, a positive phase input terminal of the preamplifier isconnected to a bias voltage, and an inverting input terminal of thepreamplifier is connected to an output end of the associated sensingline of the plurality of sensing lines.
 7. The mutual capacitive touchpanel of claim 1, wherein, from an end of each sensing line the sensingsignal is outputted, and the end of each sensing line is connected to afirst end of the selection switch by a via hole disposed on a thin filmtransistor substrate or a conductive gold spacer, and second ends of allthe selection switches are connected to the inverting input terminal ofthe preamplifier.
 8. The mutual capacitive touch panel of claim 1,wherein, the signal output unit is single and is configured to outputthe driving signals with different frequencies to the plurality ofdriving lines respectively; or a plurality of the signal output unitsare present and each of the signal output units is configured to outputdriving signals with different frequencies to each of the associateddriving lines.
 9. The mutual capacitive touch panel of claim 1, wherein,the preamplifier further comprises a feedback network containing atleast two feedback branches connected in parallel, wherein one of thefeedback branches comprises a resistor and the other of the feedbackbranches comprises a resistor and a switch connected in series, and theresistance of the feedback network is changed by controlling the turningon and off of the switches.
 10. The mutual capacitive touch panel ofclaim 9, wherein, the preamplifier further comprises a compensationnetwork containing a compensation resistor, and the inverting inputterminal of the preamplifier is connected to a compensation signalsource through the compensation resistor.
 11. The mutual capacitivetouch panel of claim 1, wherein, the signal separation unit comprises aplurality of band-pass filters, and a number of the plurality ofband-pass filters connected to the output terminal of the preamplifieris equal to a number of the plurality of driving lines.
 12. The mutualcapacitive touch panel of claim 1, wherein, the signal output unit is asignal generator.
 13. A mutual capacitive touch panel, comprising: aplurality of driving lines; a plurality of sensing lines intersectingwith the plurality of driving lines; at least one preamplifier; a signaloutput unit; and a signal separation unit; wherein the signal outputunit is disposed at input ends of the plurality of driving lines and isconfigured to simultaneously output driving signals to all the drivinglines, wherein each of the driving signals has a different frequency andis output to a different one of the plurality of driving linesrespectively; wherein the preamplifier is disposed at output ends of theplurality of sensing lines and is configured to capture sensing signalsfrom the plurality of sensing lines, and amplify the sensing signals andoutput the amplified sensing signals to the signal separation unit;wherein the signal separation unit is connected to the preamplifier andis configured to separate the sensing signals with differentfrequencies, and to obtain addresses of the plurality of driving linesassociated with each of the sensing signals; wherein the signal outputunit determines a frequency sequence every a first predetermined timeinterval based on a hopping rule, and changes a frequency of a drivingsignal of each of the plurality of driving lines based on the determinedfrequency sequence, wherein the frequency sequence comprises frequenciesof the driving signals; wherein an output end of each sensing line ofthe plurality of sensing lines is connected to the at least onepreamplifier; wherein the mutual capacitive touch panel furthercomprises a shift register and selection switches, wherein a number ofthe selection switches is equal to a number of the plurality of sensinglines; wherein an output terminal of each of the at least onepreamplifier is connected to a first end of one of the selectionswitches, and a second end of each of the selection switches isconnected to the signal separation unit; and wherein an output signal ofthe shift register is provided to a control gate of each of theselection switches.